Video sequences to be displayed by video apparatus are coded in a signal according to various possible standards. One of these standards is the VHS standard which is widely-used to record a video signal on a tape.
According to the VHS standard, the luminance signal and the chrominance signal corresponding to a frame of a given number of lines on the display are recorded on a magnetic track of the tape, the luminance signal is frequency modulated in a range between 3.8 MHz and 4.8 MHz and the encoded chrominance signal being amplitude modulated on a 627 kHz carrier. The signals for two successive fields (2 interlaced fields representing 1 picture screen) are recorded on two successive tracks. To reduce cross-talk between the two successive tracks, an azimuth recording method is employed.
This is unfortunately not sufficient to eliminate cross-talk between the low-frequency part of the chrominance signal of two successive tracks. Therefore a complicated phase-shift procedure including a 2H comb-filer (for play-back) had been introduced by the VHS standard in order to eliminate this cross-talk; the chrominance signal consequently lags for a 2-line time behind the corresponding luminance signal. This means that a conventional VHS video processor outputs a chrominance signal which relates to a line originally situated two lines above the luminance signal which is output at the same time. Stated differently, the luminance and corresponding chrominance information are vertically mis-registered. The same problem arises with the S-VHS standard.
In order to correct this inherent defect of the VHS standard, it has been proposed by patent application WO 92/22 173 to provide a video apparatus meant to use the reproduced VHS signal with a CCD-delay-line in order to delay the luminance signal, preferably for a 2H duration. The luminance signal output from the CCD-delay-line thus corresponds to the same line in the originally-recorded video sequence as the chrominance signal output from the comb filter.
Unfortunately, a 2H CCD-delay-line is expensive and has thus scarcely been used for this purpose.